Mud Oven: Insulation and the history of humanity
With the base stable and solid, we set about building the form with found cinder blocks. They are kind of ugly, but we figured we'd cement over them later and decorate the base - maybe even make a mosaic on it - later. Once the form was built, I started filling it up with all the rubble in the garage, collected over months. And then some gravel and sand to make it level about 10 inches from the top. The base has a circumference of 45 inches, and the oven interior itself will be about half that.
Next we made a layer of insulation so as to keep the energy of the oven inside of it. This layer is made up of beer bottles (glass retains heat fairly well as does the air trapped within it), encased in a mix of slip and sawdust. (Slip is basically a liquid clay-mud, of the consistency of heavy cream. You fill up a bucket with clay-mud and add water, let it sit overnight, and then stir it up evenly.) The added sawdust acts as an insulant, and over time it will get burned out, leaving a clay with lots of pores, like a sponge. And that makes a good insulant too.
So here we are mixing the slip and sawdust together. (The sawdust came from our very first raku firings a year and a half ago - it had a wonderful campfire smell.)
And here you see the packed bottles. I thought about it later and realized there should be more, and they should be packed tighter - much thanks also to Gloria's comment - so I collected more bottles and repacked everything the next night, as tight as I could with the extra 12 bottles I had.
The theme of insulation, of conserving the energy you've built up, is huge. Because if you want to build more powerful ovens and kilns - and the history of humanity has in large part been the history of raising temperatures - then you can try to get a fuel that burns hotter, sure, but if you don't also figure out how to conserve more of that heat, then you ain't going nowhere.
And as friends involved in the Craft of Fire in Mikebuda Park in Hungary pointed out, the theme of the insulation of one's own Energy or Force is also key. You've had great inspiring experiences in your life, perhaps in your spiritual work - what do you do so that they serve to keep your internal frequency high, so that they don't just leak out and dissipate into the grey world that so often seems to try to absorb us? What insulation do you use inside?
Next up: laying down the hearth.
Next we made a layer of insulation so as to keep the energy of the oven inside of it. This layer is made up of beer bottles (glass retains heat fairly well as does the air trapped within it), encased in a mix of slip and sawdust. (Slip is basically a liquid clay-mud, of the consistency of heavy cream. You fill up a bucket with clay-mud and add water, let it sit overnight, and then stir it up evenly.) The added sawdust acts as an insulant, and over time it will get burned out, leaving a clay with lots of pores, like a sponge. And that makes a good insulant too.
 |  |  |
So here we are mixing the slip and sawdust together. (The sawdust came from our very first raku firings a year and a half ago - it had a wonderful campfire smell.)
And here you see the packed bottles. I thought about it later and realized there should be more, and they should be packed tighter - much thanks also to Gloria's comment - so I collected more bottles and repacked everything the next night, as tight as I could with the extra 12 bottles I had.
 |  |  |
The theme of insulation, of conserving the energy you've built up, is huge. Because if you want to build more powerful ovens and kilns - and the history of humanity has in large part been the history of raising temperatures - then you can try to get a fuel that burns hotter, sure, but if you don't also figure out how to conserve more of that heat, then you ain't going nowhere.
And as friends involved in the Craft of Fire in Mikebuda Park in Hungary pointed out, the theme of the insulation of one's own Energy or Force is also key. You've had great inspiring experiences in your life, perhaps in your spiritual work - what do you do so that they serve to keep your internal frequency high, so that they don't just leak out and dissipate into the grey world that so often seems to try to absorb us? What insulation do you use inside?
Next up: laying down the hearth.
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